This invention relates to latching devices for securing shank-and-socket type couplings, such as for connecting auger sections used in auger mining machines to rotate a cutting head and progressively drive an auger assembly forward into a mineral deposit while removing the mined material with the auger strings. More particularly, the invention relates to a latching device of small radial dimension relative to the auger section to fit within the cross sectional limits of the hole being cut by the auger machine.
The invention has particular utility in connection with auger machines for mining lateral seams or veins of mineral, such as coal, and especially to a machine, usually located adjacent an open wall, that advances a rotary cutting head progressively laterally into the seam of coal while conveying the dislodged coal rearwardly from the cutting head with helical auger flights according to conventional practice. Additional auger sections are added as needed depending upon the extent of the advance of the cutting head into the coal seam, to form a string of endwise coupled auger sections corresponding to the depth of the hole.
Many such auger mining machines have multiple rotary cutting heads journaled in a rigid frame with their respective axes parallel and generally coplanar. The resulting assembly is advanced as a unit into the earth to cut a relatively wide hole as the mining progresses. Where multiple cutting heads are used, normally two or more separate strings of auger sections extend from the main body of the machine to the cutting head assembly to rotate the plurality of cutting heads simultaneously and to exert a thrust to advance the cutting heads into the mineral deposit to be mined.
New developments in the economics of coal mining have created conditions where it is now feasible to mine coal from relatively thin seams that in the past would have been bypassed as being economically unfeasible to mine. The relatively small diameters of the cutting heads and auger flights for mining such thin seams have necessitated the provision of associated equipment that will fit within the cross section of the hole through which the auger strings are advanced. This associated equipment includes the devices for latching the couplings between axially aligned endwise coupled auger sections in the auger strings.
Normally the interconnected auger sections have a socket portion on one end of each section and a cooperating mating shank on the opposite end. The shank fits into the socket recess of the next section, and a latch pin extending transversely of the auger axis extends through the wall of socket portion and into a recess formed in the shank. Such a connection is disclosed in U.S. Pat. No. 3,278,236. A lever is usually provided for retracting the latch pin from the shank to permit uncoupling of the section, as when the cutting head is being withdrawn from the hole at completion of the mining of the seam. As the auger string is withdrawn, the auger sections of each string must be sequentially removed from the machine by uncoupling the sections and lifting the rearmost section from the machine.
Prior art latching devices, however have not been sufficiently compact to permit their use in holes of smaller cross section that are now common.
Moreover, prior art latching devices are susceptible to being rendered inoperative by debris that enters the latching device and impairs operative movement of the latch pin.
The present invention resolves the difficulties indicated above and affords other features and advantages heretofore not obtainable.